shithub: libvpx

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vp9-noise estimation: Increase threshold for Low-level.

This make it more likely clean/low-noise content will
be set as LowLow, and hence no denoising will be done.
Also set early exit on denoising for small blocks.

Change-Id: I4a72bba3e6c5e2d523d304c39deacc9c39bf216c

--- a/vp9/encoder/vp9_denoiser.c

+++ b/vp9/encoder/vp9_denoiser.c

@@ -216,6 +216,12 @@

   if (is_skin && (motion_magnitude > 0 || consec_zeromv < 4))

     return COPY_BLOCK;

+  // Avoid denoising for small block (unless motion is small).

+  // Small blocks are selected in variance partition (before encoding) and

+  // will typically lie on moving areas.

+  if (motion_magnitude > 16 && bs <= BLOCK_8X8)

+    return COPY_BLOCK;

+

   // If the best reference frame uses inter-prediction and there is enough of a

   // difference in sum-squared-error, use it.

   if (frame != INTRA_FRAME &&

--- a/vp9/encoder/vp9_noise_estimate.c

+++ b/vp9/encoder/vp9_noise_estimate.c

@@ -91,7 +91,7 @@

   } else {

     if (ne->value > ne->thresh)

       noise_level = kMedium;

-    else if (ne->value > (ne->thresh >> 1))

+    else if (ne->value > ((5 * ne->thresh) >> 3))

       noise_level = kLow;

     else

       noise_level = kLowLow;